import java.io.*; import java.util.*; public class Main { static ArrayList> graph = new ArrayList<>(); static final int MOD = 1000000007; static int n; static int base; static long ans = 0; public static void main(String[] args) throws Exception { Scanner sc = new Scanner(); n = sc.nextInt(); int m = sc.nextInt(); base = sc.nextInt(); for (int i = 0; i < n; i++) { graph.add(new HashMap<>()); } UnionFindTree uft = new UnionFindTree(n); for (int i = 0; i < m; i++) { int a = sc.nextInt() - 1; int b = sc.nextInt() - 1; int c = sc.nextInt(); if (!uft.same(a, b)) { uft.unite(a, b); graph.get(a).put(b, c); graph.get(b).put(a, c); } } getCount(0, 0); System.out.println(ans); } static int getCount(int idx, int p) { int count = 1; for (int x : graph.get(idx).keySet()) { if (x == p) { continue; } int y = graph.get(idx).get(x); int tmp = getCount(x, idx); ans += (long)tmp * (n - tmp) % MOD * pow(base, y) % MOD; ans %= MOD; count += tmp; } return count; } static long pow(long x, int p) { if (p == 0) { return 1; } else if (p % 2 == 0) { return pow(x * x % MOD, p / 2); } else { return pow(x, p - 1) * x % MOD; } } static class UnionFindTree { int[] parents; public UnionFindTree(int size) { parents = new int[size]; for (int i = 0; i < size; i++) { parents[i] = i; } } public int find(int x) { if (x == parents[x]) { return x; } else { return parents[x] = find(parents[x]); } } public boolean same(int x, int y) { return find(x) == find(y); } public void unite(int x, int y) { parents[find(x)] = find(y); } } } class Scanner { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); StringTokenizer st = new StringTokenizer(""); public Scanner() throws Exception { } public int nextInt() throws Exception { return Integer.parseInt(next()); } public long nextLong() throws Exception { return Long.parseLong(next()); } public double nextDouble() throws Exception { return Double.parseDouble(next()); } public String next() throws Exception { if (!st.hasMoreTokens()) { st = new StringTokenizer(br.readLine()); } return st.nextToken(); } }